Also: if I make a 920x 450 px photo, would the right thing be changing the height declaration from 180 to 450 or 500?

If your image is 920px width and 450px height, you need to specify those dimensions; if you specify a number smaller than that, then you're image will be clipped (if the holding element has an "overflow: hidden;" attribute-value.

Since you want to display your whole image, then you should specify its dimensions in your declaration.

HTH

Replace your current "#title" definition with the following:

h1#title {
background:transparent url('http://path/to/new/image.jpg') no-repeat scroll center top;
height: 450px;
width: 920px;
}

Notice that I added the "h1" element to the "#title" selector; that forces the browser to apply the new dimensions you're specifying. An alternative to preceding the selector with the element is like this:

#title {
background:transparent url('http://path/to/new/image.jpg') no-repeat scroll center top;
height: 450px !important;
width: 920px !important;
}

Try either one.

HTH

My suggestion would be to limit the height of the header image to 450px maximum so that at the very least the top navigation would show. That said, it is your choice.

All you have to do is change the height declaration value in #title from 180px to whatever you want, then upload the image to your media library and change the header URL in the #title to the newly uploaded URL.